Radio telephone system



April 15, 1930. E. E. CLEMENT RADIO TELEPHONE SYSTEM Filed Feb. 9, 19244 Sheets-Sheet gmentot April 15, 1930. E. E. CLEMENT RADIO TELEPHONESYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 2 A ril-15,1930. Ef CLEMENT1,154,817

RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 3 April 15,1930.

E. E. CLEMENT RADIO TELEPHONE SYSTEM Filed Feb. 9, 1924 4 Sheets-Sheet 4Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE EDWARD E. CLEMENT, OFWASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO EDWARD F. OOLLAIDAY, OFWASHINGTON, DISTRICT OF COLUMBIA RADIO TELEPHONE SYSTEM Applicationfiled February 9, 1924. Serial No. 691,825.

'My invention relates to radiowire systems of broadcast distribution,with special reference to the use of electric light, power, railway orother wired circuits, so that the wires may be employed for transmittingmodulated waves, metering, and other purposes. This application is acontinuation in part .of my,

phone system, either automatic or manual,

and broadcast to said instruments from a central station which may bethe centralpower station or a substation belonging to the system or thetelephone central station or a substation thereof. In any case the radiooperators are provided with telephone switching means whereby they canconnect. themselves to various radiophone stations for purposes ofobservation and supervision of the system. At the radiophone stations, Iprovide local switching connections to the current mains, and throughthese connections when closed eifect current feed to the instrument formetering, and also bring to the instruments modulated carrier currenttransmitted from the central station referred to. This central stationis provided with amplifying and modulating apparatus for originalmatter, and with relaying apparatus for distributing to the localsubscribers signals received from a distance. By thus organizing acombination system, it is possible to unify the service in allrespects-and to make service charges on a fair and accurate basis. I maymeter the service, using asimple constant speed current meter, withmeans to register units of time use, or to register the number of timesan instrument is used. In the latter case, the

meter may be reduced to ultimate simplicity, being in effect nothingmore than a record- 1ng magnet cooperating with a suitable switchservice. 11 any case, it' is intended that the subscribers instrumentshall be adapted to receive by pure radio waves from a distance, forwhich no meter charge should be made, and also adapted to receivemodulated waves transmitted over the wired network, for which a chargeshould be made. For this purpose, I make the subscribers in strumentwith an antenna circuit and coupler coil, a detector tube, andpreferably one stage of audio amplification to permit the use of a loudspeaker, together with heterodyne coupler. connected through switchcontacts to the wired network, so that the instrument will function as asuperheterodyne receiver when taking waves from both the ether and thewires. I further provide the plate circuit with a tickler coil, normallydisconnected therefrom and the plate circuit closed on itself, butadapted to have its circuit closed through plate when theheterodyningcigguits to the wirednet work are broken. Thus theinstrument will function as a heterodyne receiver, or by disconnectingthe heterodyne coupler and connecting the tickler coil, may 7 be used toreceive pure radio waves from distant stations direct. The meter circuitwill be closed-"onlywhen the heterodyne circuit is closed. I

It is to be understood that the principles herein set forth are notlimited to the use of lighting power or railway circuits as such, or toany particular type of telephone system, although I shall describe andclaim herein a manual telephone exchange system of standard WesternElectric type.

It is to be further understood that I am not limited to the specificcircuits and connec tions shown by which my subscribers instrument ismade a combination receiving instrument, and especially a combination ofheterodyne and regenerative receivers, for the purposes stated. Such aninstrument may be useful in other inventions, and it is also to beobserved that the method of metering, by which a record is made of thepay service stead of time of use.-

only, may be useful for various other connections.

My invention is illustrated in the accompanying drawings, in which: t

Fig. l is a typical diagram showing a radiophone system combined with anelectric lightingi system.

. 2 is a diagram of a single radiophone Fig. 7 is a similar detail of amodified form of meter to record number of connections in- Referring tothe drawings, Fig. 1 is a condensed diagram showing an electric lightingsystem with a central power station 0, five transformer substations, C,C C", C, C, consumers mains M fed from the substations, and feeder mainsM, distributing the power from the main generating plant typified by Gto the substations. At the central station Sw indicates the usual mainswitchboard, and Sw a supplemental switchboard for urposes to bedescribed. -From this board Sw' communication wires 35, 37, 39, 41

extendout to the substations, one pair of more.

accompanying each feeder cable in the ducts. At each substation a smallswitchboard S10 is provided, equipped with an automatic selective switch36, 38, 40 or 42, having a switch arm or wipers connected to theincoming, line I 35, 37, 39 or 40, and contacts over which the wipersare stepped in operation, to connect with local lines to consumersradiophone stations. Thus at substation C the switch 36 has contactsconnected to wires 43, 44, which extend from that substation to theradiophone stations 43", 44. This same substation C carries a feedermain M to a second transformer station 0, and the accompanyingcommunication wire 45 extends to a switch 46 at said substation, fromwhich wires 47, 48 extend to radiophone stations 47, 48*. Thissubdivision of the system requires an extra digit in the numbertransmitted from the central operators dial 32 or switchboard 811) atcentral station C, the switches 34, 36, and 46 corresponding to firstand second selectors and connectors in an automatic telephone system. Nodetail of the switching circuits or the operating mechanism of theautomatic switches is given herein, as such circuits and switches arewell known, and of themselves form no part of the present invention, the

main feature of which as regards the communication circuits, lies in theability of the central ofiice operator to automatically connect himselfto any part of the system through the minimum number of wires,comprising in this case a single pair from the central station to eachsubstation, and single pairs diverging therefrom to the furthersubdivisions of the system. The last link in any of these circuits isthe individual drop wire, extending from a terminal box to'the buildingin which current is to he used. These drop wires are relatively short,and we contemplate employing them for a double purpose, viz., forcommunication by telephone or otherwise over the wires, and as antennaefor the radiophone instruments, where found expedient or desirable. Thiswill be described hereinafter.

Transformers K are the substation transformers, and transformers K arethe house or pole transformers feeding the consumption circuit M fromthe house mains M. The consumption circuits M carry translatingdevicessuch as lamps L, and also supply current to the radiophonereceivers RR, to be presently described. These radiophones are allstandardized and of uniform design and construction, and are calibratedand locked-when installed, so as to receive on common wave length only,i. e., thewave length alloted to the broadcasting transmitter RT at thecentral station C. This transmitter maybe located at some other pointthan the central power generating staerator at switchboard Sw, who isalso to listen in andobserve the operation of the outlying instruments.

The central station is equipped with a local oscillator 0G to send wavesat heterodyning frequency over thewired network M, through the switch-60 and the coupler CC to the switchboard Sw. These waves may bemodulated by the local modulator LM.. The central station may alsotransmit by pure radio waves from the local oscillator OC', and thesewaves may be modulated by closing the switch 62-62, the waves fromoscillator OC being left unmodulated if desired by opening the contacts61-451.

The net result of this arrangement is that the subscribers instrument inFig. 2 can be supplied with pure radio waves over the ant'enna 25,modulated or umnodulated, with heterodyning waves over the lightingcircuits M, M, M, either unmodulated or modulated; and these waves mayeither be relayed from the central ofiice after radio amplification, orthey can originate there.

Referring now toFig. 2, we have therein shown a portion of the Y powerand communication circuits, one radiophone RR, and

the general arrangement of a radio operators sumers station (telephonesbeing provided) may be connected to the radio transmitter forbroadcasting as provided in Reissue Pat- .ent 16,231 hereinbeforereferred to., This e11- ables the operators to bring in contributions tothe broadcasting programme, and also to organlze groups of subscribersfor broadcast meetings on subjects of common interest,

. such as chess games,-debates, etc. In such cases, thevarioussubscribers lines 30*, 31 of any desired group are all plugged in on thesameScircuit 30.31 to'the central broadcastingfstation, where they maybe put on the transmitter RT asa group through ack J 5 and "suitableamplifying apparatus.

The feeder-did extends from transformer substation C to the housetransformer K which supplies\main M carrying lamps L. To this main ashcket is connectedwith which a plug P cooperates to connect the feedwires 17-18 of the radiophone receiver RR. Current for the meter RM issupplied through this circuit. This meter as shown comprises a motor 22driving a Veeder counter, 24, through a worm gear 23, and taking currentthrough branch wires 1920. The motor may be of any standard type adaptedto the current employed. In tne present case alternating current atcycles, single phase, is presupposed, and the'motor may be a singlephase synchronous or split phase machine, or

any other capable of operating at constant speed on a constantpotential. The Veeder counter is marked in time-use units.

In the receiving instrument 28 is a coupler, on the input side of thecombined heterodyne and regenerative receiver. vWaves received over theantenna 25 pass through the tuned circuit to the tube detector 6d,while. waves received from the wired circuit M pass through the closedswitch contacts 3 to the heterodyning coupler kc and thence to thedetector. The combined input is detected and rectified and by theamplifier tube at delivered to the loud speaker 56 through thetransformer 14;. The plate circuit of the tube ta? is normally closed at3,1, which can be opened and contacts .2 closed to connect the ticklercoil to in the plate circuit, this tickler being incharge is made.

ductively associated with the coupler coils 28.

To receive combined waves over the wires and the ether, switch a isopened and all the switch contacts 3/ are closed; while to receive asingle train of pure radio only, which would be public broadcastingservice, the contacts y are all opened, and the contacts z closed. Thiscuts oif the energizing current from the meter, cuts-off theheterodyning coil he, and connects the tickler coil to. It is to benoted thatthe subscriber in this arrange ment and in many other similarhook-ups,

can receive with practically equal efficiency over either circuit, byheterodyning or regeneration, but the former will give more satisfactoryresults because of the greater amount. of energy and better servicedelivered over the wires, for which of course a In practice, themiscellaneous independent use of the subscribers instrument would hecovered by a flat rental charge.

It should be observed that if desired the co'ntactsz may be closed andthe associated contacts y may be opened, in order to add theregenerative effect to the heterodyning through the two input circuits,a separate switch being then provided for the tickler coil and platecircuit, instead of the gang switch contacts shown in Fig. 6.

For purposes'oftesting and observation, the telephone transmitter T maybe located in proximity to the horn of the receiver 56. The telephoneequipment shown is of magneto type, (magneto-generator and ringer beingomitted) with induction coil I and receiver t.v When placed as shown andplugged throughto central station C, the radio op erator canlisten tothe receiver 56 over wires 30-3O-3131 Referring now to Fig. 3, we haveshown therein part of a system similar to that of Fig. 2, but employingan ordinary telephone exchange line 15-16 for a communication circuit.In this case the radio operator at station C has a telephone Ttconnected to'a telephone exchange switchboard G" from ceiver RR areshown. In this instrument, 1-

indicates balancing resistances, 2 the radio frequency transformers, 3the audio frequency transformers, 4 is a telephone transformer, 5 thearmature of a loud speaking receiver, .6 the field of the loud speaker,7 a vacuum tube rectifier, 8 a plate voltage tube rectifier, 9(as-stated) the power transformer,

10 the filament rheostat, 11 a condenser of one the loud speaker. Noclaim is made herein to this instrument or, its circuits, and it ispresented as typical only of any instrument suitable for use with thecurrent supplied to the mains M.

'The antenna circuit is completed from ground 29 and coil 28 or theequivalent, by wire 25 to plug P, and so to the lighting mains whichthus become part of the antenna. We have shown condensers 26-27 of smallcapacity in this circuit, but any other known means of preventingcurrent leakage from the, lighting mains may be employed.

For rendering measured service, meter RM is provided, its circuit wires1920 being bridged across the main feed wires 1718 ofthe radiophone set.The constant speed motor '22, gears 23 and counter 2d are the same asbefore. The meter records time-use, as the circuit 17-18 is closed onlywhen the radiophone is in service. An advantage in having the meterforming a part of the instrument equipment is that the entire equipmentis thereby made portable and may be carried to any point where ]acks J aor J b are installed, in the same or another building, and the serv icewill be uniformly metered for all such use. In order topermit suchportable use, and for other purposes to be explained, the various partsare assembled in two separate units, as illustrated in Fig. 4, whereinRU is a box containing the power'supply, including in the casedescribed, the special transformer 9, with five windings and therectifier tubes 7 and 8; and AU is a separate box containing theamplifier tubes, amplifier transformers, and other apparatus. By thusdividing the set, advantages are gained, viz., the amplifier isjemovedfrom immediate proximity to the power supply apparatus, from which itmight pick up a hum, and second, the power supply box can be madeinterchangeable with others containing different sources of supply, suchas a set ofstorage batteries or a special equipment for adapting 1-10volt direct current supply to the feed circuits of filaments and plates,etc. For this purpose a small motor transformer may be employed, orsuitable rheostats and switches. In any case the meter motor is placedin the same box RU with the power equipment and the dial arranged in theside of the box to be read from the outside. Where the box contains astorage battery, the meter is thus made a part of the battery unit RUand taken to a central station or 'service station for charging. Wecontemplate organizing this service on such a basis that three classescan be provided fori first those consumers who have alternating currentsupply on their premises, as herein illustrated; second those who havedirect current ing, where the meter will be be read and the record ofsuch readings will be periodically used in billing for the service. Tosave time in such cases, and according to similar practice. in otherlines of business, the battery units RU may all be made interchangeable,and the meter readings of each unit' will be recorded, on receipt anddelivery. By this means, a discharged battery can be exchanged at theservice station for a freshly charged battery without delay. As thekeeping of such records is in accordance with well known principles,detailed description is unnecessary. I lay no claim herein to adetachable power unit broadly, but I shall claim herein theinterchangeable unit feature, whereby different sources of currentsupply may be furnished for a standard AU unit or instrument, and shallalso claim the mounting of the meter as apart of the power supply unitso that it will always furnish a record of time use. An incidentalfeature of this arrangement is that the box containing any RU unit maybe sealed, so that the battery, transformers, switches, rheostats andmeters are secured against interference and the meter readings therebymade dependable.

A fourth class might be added to the foregoing, including those who haveno direct connection to the lighting or power mains, but have localcurrent supply of their own. This includes surburban and other placesequipped with so-called farm lighting outfits. The voltage of such smallgenerating plants is not usually standard, but lower than that on thecity distribution systems, hence special RU units must be provided forsuch service, preferably containing storage batteries to give standardvoltages, and a suitable charging set. In any case, regular or special,the meter forms a part of the power supply unit of the radiophone, andis always connected, as herein described, when the instrument is in use.Where standard municipal current supply is available, the inspectors whoread the lighting meters will also read the radiophone meters.

Returning to Fig. 1, the drop wires such as 43, 44, 45, leading from thelocal distribution centers or substations to the consumers radiophonestations, may be used as antennae instead of the separate antennaeindicated in 2, or the lighting mains indicated in Fig. 3. In such caseplug and jack connections similar to PJ a of Fig. 3 may be em ployed, orthe anteimia connection may be permanent, the drop wire being connecteddirect to the wire in Fig. 3, with or without the "interpositionof smallcapacity condensers, as

may be found desirable. The result of making such a connection is shownin a typical diagramin Fig. 5, wherein BB is the radio phone, 0 thecentral olfice, -451 the communication wire, and T the central operatorstelephone. The communication wires ary circuit of the loud speakingtransformer on the audio side of the set, so that no telephone isrequired at the radiophone station. The circuit 3031 is thus at onceantenna and an extension of the localradio receiving circuit, over whichthe operator can test and listen directly. v

In the system ofFig. 2, a subscriber'desiring radio service, plugs hisset in on the line M through means of the plug-P, which supplies. powerto his receiving set RR through i conductors 17 -18 and to the metermotor 22 through branch wires 1920. The meter therefor starts intooperation and continues toerecord the length of time the connection ismaintained. The receiver RR, being supplied with power will now pick upthe broadcast signaling to which it is tuned through the antennacircuit2528 and translate it into amplified audible signals through thetransformer 14 and loud speaker 56 in a manner as will be understood bythose skilled in the art. In the present instance the receiver ER istuned to the transmitting station RT so that broadcast matter .isreceived there-- from.

Should the subscriber desire connection with the central ofiice 0 he candoso through the use of his telephone set T, t over the line 30-31through the plug and jack connection J Fe-P at the substation G and overline 30-31, to station G, all in the usual manner as well understood inthe art of telephone communication, details such as switching and 30 31v are here shown connected also to the seconders loudspeaker through thetransmitter T, which observation enables the operator to adjust thetransmitter to the subscribers instruments which latter are permanentlytuned to a common predetermined wave length.

Where storage batteries are used as a source of power supply with thetime use metera part of the power supply unit, as indicated.

in Fig. 4 theoperation is similar to that previously described exceptthat instead of the subscriber connecting with the common distributingsystem he connects his set with the portable source'of power supply,receiving the signalling energy through his independent aerial as inFigs. 1 and 2, or a distributing system used as an aerial as in Figs. 3and 5.

' The storage battery and metering features described above and nbtclaimedherein, are

network, and other means for broadcastingsimultaneously, properlyrelated unmodulated waves through the ether.

In testimony whereof I hereunto affix my signature. I r a EDWARD E.CLEMENT.

signaling means and'their use being omitted I from the drawing anddescription for the sake of clearness. Similarly, the central stationoperator may be connected with the subscribers telephone set over theline 30-81 and 3O '31? through the substation C5. Thus the subscribermay communicate with the cen- I tral station for information or toreport condition of service. When it is desired to have the subscriberbroadcast, the above described connection is established and furtherextend.- ed through jacks J 2 and J 5 and suitable cord and plugconnections, not shown, to the radio transmitter RT. 5

F or" supervision of the quality of reception by the subscribers radioreceiver, and controlling the quality of reception, the operator.

at the central station C makes use of'the telephone connection abovedGSCIlbBd tO listen in on the audio reproduction from the subscrib-

